Water Treatment Coagulant

Here's some info, as well as a possible better alternative.

http://www.wwdmag.com/Primary-Coagulant-Aid-Outperforms-Alum-Slashes-Operating-Costs-article2709

The chemical formula for alum is: Al2(SO4)3, there is usually water of crystallization attached to the alum molecule as well. There are other alums also, but they are usually designated with the name of the other sulfate such as: ammonium, potassium, etc. i.e. potassium alum.

Talking of alum used as coagulant, I wish to share some information on the use of Moringa Oleifera seeds for use as water coagulant. Communities spread across India and Africa have been using Moringa seeds having the capacity of purifying even the most turbid water. The purifying activity is because the seeds contain biologically active coagulant. Moringa seeds will clear water as an inexpensive traditional method of making drinking water safe to the local folks. You will need 15 seeds to purify 20 litres of water. The seeds are crushed into a thick paste and then mixed with water. The paste coagulates the suspended particles in water which later settle down.